TWI627307B - Surface-treated copper foil for printed wiring board, copper-clad laminate for printed wiring board, and printed wiring board - Google Patents

Abstract

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on the surface on which roughened particles are formed, characterized in that the average height of the roughened particles on the surface of the silane coupling agent layer is 0.05 μm or more Up to 0.5 μm, the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more.

Description

Surface-treated copper foil for printed wiring boards, copper-clad laminates for printed wiring boards and printed wiring boards

The present invention relates to a surface-treated copper foil for printed wiring boards. In addition, the present invention relates to a copper-clad laminate for a printed wiring board using the surface-treated copper foil for a printed wiring board and a printed wiring board using the surface-treated copper foil for the printed wiring board.

In recent years, with the development of high-performance, high-functioning computers or information communication equipment, or the development of the Internet, it is necessary to transmit large-capacity information in a faster manner. Therefore, the transmitted signal tends to be more high-frequency, and the printed wiring board is required to suppress the transmission loss of the high-frequency signal. In the production of a printed wiring board, a copper-clad laminate in which laminated copper foil and an insulating base material (resin substrate) are heated and pressurized is generally produced, and a conductor circuit is formed using the copper-clad laminate. When transmitting a high-frequency signal (high-frequency transmission) to the above conductor circuit, the transmission loss is related to the three elements of conductor loss, dielectric loss, and radiation loss.

The conductor loss is caused by the surface resistance of the conductor circuit. After transmitting high-frequency signals in a conductor circuit formed by using a copper clad laminate, a skin-effect phenomenon occurs. That is, when alternating current circulates in the conductor circuit, the magnetic beam changes, and a back electromotive force is generated in the center of the conductor circuit. As a result, it is difficult for current to flow in the center of the conductor, but the surface portion (skin portion) of the conductor The phenomenon of increased current density. This phenomenon of skin effect reduces the effective cross-sectional area of the conductor and produces the so-called surface resistance. Current The thickness of the flowing epidermis (skin depth) is inversely proportional to the square root of the frequency.

In recent years, high-frequency compatible devices such as over 20 GHz have been developed. When the frequency transmits high-frequency signals in the GHz band in a conductor circuit, the skin depth is formed to be about 2 μm or less, causing current to flow only on the extreme surface layer of the conductor. Therefore, in the copper-clad laminate used in the high-frequency compatible device, if the surface roughness of the copper foil becomes larger, the transmission path of the conductor formed by the copper foil (that is, the transmission path of the skin part) will also Lengthening increases transmission loss. Because of this, it is desirable to reduce the surface roughness of the copper foil of the copper-clad laminate used in high-frequency compatible models.

On the other hand, the copper foil commonly used in printed wiring boards is to form a roughening treatment layer (a layer for forming roughened particles) on the surface by means of electroplating or etching. Anchoring Effect) to improve the adhesion with the resin substrate. However, if the roughened particles formed on the surface of the copper foil are increased in order to effectively improve the adhesion with the resin base material, as described above, the transmission loss will increase.

The dielectric loss is caused by the dielectric constant or tangent loss of the resin substrate. When the pulse signal flows through the conductor circuit, the electric field around the conductor circuit changes. When the period (frequency) at which the above-mentioned electric field changes is close to the relaxation time of the polarization of the resin base material (movement time of the polarization-generating charged body) (that is, after high-frequency increase), delay will occur in the change of the electric field. In this state, molecular friction occurs inside the resin and heat is generated, causing transmission loss. In order to suppress this dielectric loss, as the resin substrate of the copper-clad laminate, it is necessary to use a resin with a large polarity and a small amount of replacement groups, or a resin with a large polarity and no replacement groups, so that It is difficult to cause polarization of the resin base material accompanying changes in the electric field.

On the other hand, in addition to forming the roughened layer, the copper foil used in the printed wiring board is also treated with a silane coupling agent to chemically enhance the surface of the resin foil. Adhesion. In order to improve the chemical adhesion between the silane coupling agent and the resin substrate, the resin substrate must have a certain degree of large polar substituents. However, in order to suppress dielectric loss, the use of a low-dielectric substrate that reduces the amount of highly polar substituents in the resin substrate will result in a reduction in chemical adhesion, making it difficult to ensure sufficient adhesion between the copper foil and the resin substrate Continuity.

In this way, in copper-clad laminates, there is a trade-off relationship between suppressing transmission loss and improving (improving durability) the adhesion (adhesion) between the copper foil and the resin substrate.

In recent years, high-frequency compatible printed wiring boards have rapidly developed in fields where reliability is more demanded. For example, the use of printed wiring boards for mobile communications such as in-vehicle applications requires high reliability that can be used even in severe environments such as high-temperature environments. In order to meet this requirement, in the copper-clad laminate, the adhesion between the copper foil and the resin substrate must be highly improved, for example, it is required to withstand the rigorous experiment of 1000 hours even at a temperature of 150 ℃ Sex.

In order to meet these needs, various technologies have been developed. For example, Patent Literature 1 describes a surface-treated copper foil that forms roughened surfaces with a surface roughness Rz of 1.5 to 4.0 μm and a brightness value of 30 or less in order to attach roughened particles to the copper foil. It exhibits a slightly uniform distribution at a specified density, and the surface-treated copper foil has protrusions formed by the roughened particles. The protrusions have a specified height and width, and are also described in Patent Document 1. By using such surface-treated copper foil, the adhesion between the liquid crystal polymer and the resin substrate for high-frequency circuit boards can be improved.

From the viewpoint of easy wiring or light weight, a flexible printed wiring board (hereinafter, abbreviated as FPC) is used in a small electronic device such as a smartphone or a tablet. In recent years, with the high performance of these small electronic devices and the tendency to increase the signal transmission speed, impedance matching (matching of output impedance and input impedance) of FPC has become an important issue. In order to achieve impedance matching for the high-speed signal transmission speed, measures have been taken to thicken the resin substrate (typically polyimide) as the basis of FPC.

In addition, Patent Document 2 on FPC describes an FPC suitable for use in a die soft mold package (COF) format. The electrolytic copper foil included in the FPC is configured to include The surface roughness (Rz) of the surface of the rust-preventive treatment layer formed by the nickel-zinc alloy is 0.05 to 1.5 μm, and the specular gloss at an incident angle of 60° is 250 or more. According to the disclosure of Patent Document 2, this FPC shows excellent light transmittance, and the adhesion between the copper foil and the resin substrate also shows good shape.

In addition, Patent Document 3 describes a surface-treated copper foil, in order to form roughened particles by roughening, the average roughness Rz of the roughened surface is set to 0.5 to 1.3 μm, and the gloss is set to 4.8 ~68. The ratio A/B between the surface area A of the roughened particles and the area B obtained by viewing the roughened particles from the copper foil surface side in plan view is set to 2.00 to 2.45. Patent Document 3 also describes that a copper-clad laminate formed by laminating the above-mentioned surface-treated copper foil and a resin substrate has good transparency of the resin after etching away the copper foil, and the adhesion between the copper foil and the resin also shows good shape .

【Prior Technology】 Patent Literature

Patent Document 1: Japanese Patent No. 4833556

Patent Document 2: Japanese Patent No. 4090467

Patent Document 3: Japanese Patent No. 5497808

The surface-treated copper foil described in the above-mentioned Patent Document 1 has excellent adhesion to a resin substrate corresponding to a high frequency. However, the copper-clad laminates using this kind of surface-treated copper foil have high transmission loss in the high-frequency band of the GHz band, and cannot fully meet the high requirements for high-frequency corresponding printed wiring boards.

In addition, the electrolytic copper foil used in the FPC described in the above Patent Document 2 is not roughened, and besides COF, it cannot achieve the high adhesion to the resin substrate required in the printed wiring board .

In addition, the surface-treated copper foil described in Patent Document 3 described above has insufficient adhesion to a resin base material at high temperatures. Therefore, the printed wiring board using this kind of surface-treated copper foil, for example, under the severe conditions of a temperature of 150°C and 1000 hours, cannot meet the requirements of high reliability.

An object of the present invention is to provide a surface-treated copper foil for a printed wiring board as described later. By using the surface-treated copper foil for a printed wiring board, the transmission loss is highly suppressed even when a high-frequency signal in the GHz band is transmitted, and Even at high temperatures, the adhesion between the copper foil and the resin substrate is improved, and it has excellent durability under severe conditions, and a printed circuit board that is difficult to short-circuit can be obtained. In addition, an object of the present invention is to provide a copper-clad laminate for a printed wiring board using the surface-treated copper foil for a printed wiring board, and a printed wiring board (circuit board) using the surface-treated copper foil for the printed wiring board.

The above-mentioned problems of the present invention can be solved by the following means.

[1] A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on the surface on which roughened particles are formed, wherein the average height of the roughened particles on the surface of the silane coupling agent layer is 0.05 μm or more and Less than 0.5 μm, the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more.

[2] The surface-treated copper foil for a printed wiring board according to [1], wherein the average height of the roughened particles on the surface of the silane coupling agent layer is 0.05 μm or more and less than 0.3 μm.

[3] The surface-treated copper foil for printed wiring boards according to [1] or [2], wherein, on the surface of the silane coupling agent layer, the fine surface coefficient Cms is 0.6 or more and less than 2.0.

[4] The surface-treated copper foil for printed wiring boards according to any one of [1] to [3], wherein the surface on which the roughened particles are formed has a nickel-containing metal treatment layer, which is formed in the metal treatment layer The amount of nickel element contained is 0.1 mg/dm ² or more and less than 0.3 mg/dm ² .

[5] The surface-treated copper foil for printed wiring boards according to any one of [1] to [4], wherein the amount of silicon element contained in the silane coupling agent layer is 0.5 μg/dm ² or more and is not up to 15μg/dm ² .

[6] The surface-treated copper foil for printed wiring boards according to any one of [1] to [5], wherein the silane coupling agent has a group selected from epoxy groups, amine groups, vinyl groups, (meth)acrylic At least one functional group among an acyl group, a styryl group, a urea group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group.

[7] A copper-clad laminate for a printed wiring board, wherein a resin layer is laminated on the surface of the silane coupling agent layer surface of the surface-treated copper foil for a printed wiring board of any one of [1] to [6].

[8] A printed wiring board using the copper clad laminate for printed wiring board of [7].

The surface-treated copper foil for a printed wiring board of the present invention is used in a conductor circuit of a printed wiring board to obtain a printed wiring board having excellent durability under severe conditions and superior insulation reliability. It can highly suppress the transmission loss when transmitting high-frequency signals in the GHz band, and even at high temperatures, can improve the adhesion between the copper foil and the resin substrate (resin layer).

The copper-clad laminate for a printed wiring board of the present invention is used as a substrate of a printed wiring board, and the obtained printed wiring board has a highly suppressed transmission loss when transmitting a high-frequency signal in the GHz band, and even It can still improve the adhesion between the copper foil and the resin substrate at high temperatures, and the durability under severe conditions is also superior, and it has excellent insulation reliability.

The transmission loss of the printed circuit board of the present invention when transmitting high-frequency signals in the GHz band is highly suppressed, and the adhesion between the copper foil and the resin substrate can be improved even at high temperatures, and the durability under severe conditions The performance is also superior, and it is more difficult to produce a short circuit.

The above and other features and advantages of the present invention can be clearly understood with reference to the drawings and the following description.

FIG. 1 is an explanatory diagram showing an example of a method for measuring the height of coarsened particles.

FIG. 2 is an explanatory diagram showing an example of a method for measuring the height of coarsened particles.

The preferred embodiment of the surface-treated copper foil for printed wiring boards of the present invention will be described below.

[Surface-treated copper foil for printed wiring boards]

The surface-treated copper foil for printed wiring boards of the present invention (hereinafter, simply referred to as "surface-treated copper foil of the present invention") is treated with a silane coupling agent (that is, a silane coupling agent is formed on the surface on which roughened particles are formed) Layer) the surface on which the roughened particles are formed (the surface to which the anticorrosive metal is attached as required), on the surface of the silane coupling agent layer (the surface of the surface-treated copper foil), the average height of the roughened particles is 0.05 μm or more and not Up to 0.5 μm, the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more. When the surface-treated copper foil of the present invention is treated with a silane coupling agent on both sides, and the surface after the treatment has roughened particles with an average height of 0.05 μm or more and less than 0.5 μm, as long as the BET on at least one side The surface area ratio may be 1.2 or more, or the BET surface area ratio of both sides may be 1.2 or more.

In the surface-treated copper foil of the present invention, it is the surface of the silane coupling agent layer, and the average height of the roughened particles measured on the surface is 0.05 μm or more and less than 0.5 μm, and the BET surface area ratio of the surface reaches 1.2 The above surface is simply called "roughened surface". Although the roughened surface can preferably be covered with the silane coupling agent as a whole, as long as the effect of the present invention can be achieved, the silane coupling agent may also cover only a part of the roughened surface (that is, as long as the The effect of the invention is permissible even if a part of the silane coupling agent layer on the roughened surface has a film defect, and this form is also included in the "form with a silane coupling agent layer" in the present invention).

In the surface-treated copper foil of the present invention, only at least one side may be a roughened surface, or both sides may be roughened surfaces. The surface-treated copper foil of the present invention is generally roughened only on one side The shape of the treatment surface.

In the surface-treated copper foil of the present invention, even if the average height of the roughened particles does not reach 0.5 μm and is relatively low, the BET surface area ratio is still greater than 1.2 or more. Therefore, when the copper foil and the resin layer are surface-treated by this roughening area layer surface to produce a copper-clad laminate, the alignment effect of the roughened particles and the large surface area will highly enhance the height between the copper foil and the resin layer The adhesion is good, and the copper-clad laminate with excellent heat resistance is obtained. In addition, since the roughened surface has an average height of roughened particles that is less than 0.5 μm, it is relatively low, so that the influence of the existing roughened particles on the transmission path length can be reduced. Therefore, in the conductor circuit using the copper-clad laminate, when transmitting high-frequency signals in the GHz band, the transmission loss can also be effectively suppressed.

Prior to this, even if fine roughened particles with an average height of less than 0.5 μm were formed on the surface of the copper foil, a method of increasing the BET surface area ratio to 1.2 or more was not known. In this situation, the inventors succeeded in producing coarse particles having an average height of 0.05 μm or more and less than 0.5 μm by using specific roughening plating conditions described below, and the BET surface area ratio reached 1.2 The above copper foil surface completes the present invention.

From the viewpoint of maintaining high adhesion to the resin substrate and reducing transmission loss more effectively, the average height of the roughened particles in the roughened surface is preferably 0.05 μm or more and less than 0.5 μm, more preferably 0.05 μm or more and less than 0.3 μm. The average height of the roughened particles on the roughened surface is measured by the method described in the examples described later.

In the present invention, the roughened particles are preferably formed in a uniform (homogeneous) shape across the roughened surface. The average height of the roughened particles is measured by the method described in the examples described below.

The above BET surface area ratio is calculated by the BET method according to the surface area measurement method. That is, the BET surface area ratio is such that gas molecules with a known occupied area are adsorbed onto the surface of the sample, and the surface area of the sample (BET measured surface area) is obtained from the amount of adsorption, and subtracted from the BET measured surface area. The value of the surface area (sample cut-out area) of the sample surface without unevenness, and the ratio of this value to the sample cut-out area is the BET surface area ratio, which was measured by the method described in the examples described later.

In the surface-treated copper foil of the present invention, the larger the ratio of the BET surface area of the roughened surface, the larger the surface area. Therefore, the larger the BET surface area ratio of the roughened surface is, the more the interaction with the resin is improved, and the alignment effect of the roughened particles improves the adhesion between the copper foil and the resin layer when the resin layer is laminated. In the surface-treated copper foil of the present invention, the BET surface area ratio of the roughened surface is preferably 1.2 or more and 10 or less, and more preferably 1.2 or more and 4 or less.

In the measurement of the surface area of copper foil, the measurement of the surface area using a laser microscope is generally adopted. In principle, the measurement of the "negative" portion that cannot be reached by the laser light due to the roughened particle shape is impossible. In addition, it is also difficult to detect the surface area of extremely fine concave-convex parts by means of high sensitivity. For example, even if it is a roughened particle with the same height and diameter, comparing the roughened particles retracted at the root with the roughened particles without shrinkage, although the area of contact with the resin is larger, it is the former, but it is carried out by a laser microscope. In the measurement of the surface area, it shows almost the same measured value.

In contrast, in the measurement of the surface area by the BET method, since the surface area is measured by the adsorption of gas molecules, it has a higher sensitivity to fine irregularities, and can also be measured as "negative" for laser light. "part. Thus, compared to using a laser microscope In the case of performing the measurement, in general, the surface area of the sample on which the coarsened particles have been formed can be measured with high accuracy.

The inventors succeeded in increasing the ratio of the surface area of the "negative" part or the fine concave-convex part that could not be measured by a laser microscope by performing a specific roughening plating process described later. In this way, the average height of the coarsened particles is suppressed, the transmission loss when transmitting high-frequency signals is effectively suppressed, and at the same time, it is found that the adhesiveness with the resin substrate can be greatly improved, thereby achieving cost invention.

The fine surface area coefficient (Cms) refers to the comparison value of the surface area ratio measured by the BET method relative to the surface area ratio measured by the laser microscope, which is the "negative" part that cannot be measured in the laser microscope Or the result of quantifying the ratio of the surface area of the fine uneven portions. The details of the calculation method of Cms are the same as those described in the embodiments described later. In the surface-treated copper foil of the present invention, the Cms of the roughened surface is preferably 0.6 or more and less than 2.0. By forming the Cms of the roughened surface to be 0.6 or more and less than 2.0, the adhesion between the surface and the resin substrate can be further improved to obtain a copper-clad laminate with excellent reliability at high temperatures.

In the surface-treated copper foil of the present invention, when the Cms of the roughened surface is too large, the adhesion at a high temperature tends to slightly decrease. The reason for this has not yet been determined, but it can be inferred that when the surface area ratio of fine irregularities that cannot be measured in a laser microscope is too large, the uneven portions that are not filled with resin tend to remain as voids, and the voids are used as The starting point will accelerate the oxidation of copper at the resin interface during heating, causing one of the reasons for the decrease in adhesion.

In addition, in the surface-treated copper foil of the present invention, the Cms of the roughened surface may not reach 0.6, but when the Cms is too small, there is a tendency to reduce the adhesion at high temperatures. Although the detailed mechanism is inconclusive, the so-called Cms is too small, which means that there is no The "negative" part measured by the method, or the proportion of the fine uneven part is less, it can be inferred that the mechanical adhesion effect (generally, also known as the calibrated effect) is reduced, making it easy to accelerate at high temperatures One of the reasons for the oxidation of copper at the resin interface. Therefore, the Cms of the roughened surface is preferably 0.6 or more and less than 2.0, and more preferably 0.8 or more and less than 1.8.

In addition, between the surface area measured by the laser microscope and the surface area measured by the BET method, since the measurement principle of the surface area is different, there may be cases where Cms is less than 1 depending on the shape of the roughened surface.

In the surface-treated copper foil of the present invention, the surface on which roughened particles are formed before the silane coupling agent treatment is made of chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu ), zinc (Zn), molybdenum (Mo), and tin (Sn), a metal treatment layer selected from at least one metal, or preferably having a chromium, iron, cobalt, nickel, copper, zinc, molybdenum, and tin selection A metal treatment layer of an alloy formed by at least two metals. The metal treatment layer is a metal treatment layer having at least one metal selected from nickel, zinc, and chromium, or preferably a metal treatment having an alloy formed of two or more metals selected from nickel, zinc, and chromium Floor.

In the manufacturing process of the copper-clad laminate or printed wiring board used for the surface-treated copper foil of the present invention, for example, the bonding process between the resin and the copper foil, or the welding process, etc., are often heated. By this heating, copper is diffused to the resin side, although the adhesion between copper and resin is reduced, but by providing the above-mentioned metal treatment layer, the diffusion of copper can be prevented, and the resin substrate can be more stably maintained. Between the high degree of tightness. In addition, the metal constituting the metal treatment layer can also act as a rust-proof metal to prevent copper rust

From the viewpoint of further improving the etching properties of copper foil, it is also very important to control the amount of nickel as an anti-rust metal on the surface where roughened particles have been formed before the silane coupling agent treatment. That is, when there is a large amount of nickel adhesion, although copper rust is hard to be generated and the adhesion between the resin and the resin at a high temperature tends to be improved, nickel tends to remain after etching, and it is difficult to obtain sufficient insulation reliability. In the case where the surface-treated copper foil of the present invention has a metal-treated layer, the amount of nickel elements contained in the metal-treated layer is preferably 0.1 mg/dm ² from the viewpoint of having both adhesion and etching properties at high temperatures. Above and below 0.3mg/dm ² .

[Surface-treated copper foil for the manufacture of printed wiring boards]

<copper foil>

As the copper foil used in the production of the surface-treated copper foil of the present invention, for example, rolled copper foil, electrolytic copper foil, etc. can be selected according to the application or other purposes.

The thickness of the copper foil used in the surface-treated copper foil of the present invention is not particularly limited, and can be appropriately selected according to the purpose. The thickness of the foil is generally 4 to 120 μm, preferably 5 to 50 μm, and preferably 6 to 18 μm.

<roughening plating treatment>

In the production of the surface-treated copper foil of the present invention, the roughened surface may be formed by performing roughening plating on the surface of the copper foil under specific conditions. That is, the basis of the present invention is that the inventors set the molybdenum concentration within a specific range, and by performing electroplating treatment under specific conditions described later, it was found that the roughened surface can be formed.

(Roughening plating treatment conditions)

In order to form the above roughened surface, in the roughening plating process (electroplating process), the molybdenum concentration must be controlled to 50 mg/L or more and 600 mg/L or less. If the molybdenum concentration is less than 50 mg/L, problems such as powder falling are likely to occur. In addition, if it exceeds 600mg/L, although other characteristics can be satisfied, it is difficult to treat the surface after the silane coupling agent is treated (that is, roughened The BET surface area ratio of the treated surface was increased to 1.2 or more.

In order to form the above roughened surface, in the roughening plating process, it is necessary to set the flow velocity between the electrode gaps to 0.15 m/sec or more and 0.4 m/sec or less. If the flow velocity between the electrode gaps does not reach 0.15 m/sec, the hydrogen gas separation operation on the copper foil cannot be performed, and it is difficult to obtain the molybdenum effect and cause problems such as powder flaking. In addition, when the flow velocity between the electrode gaps exceeds 0.4m/sec, the supply of copper ions to the fine recesses will be excessive, making the recesses buried by electroplating, making it difficult to increase the BET surface area ratio of the surface treated with the silane coupling agent to 1.2 the above.

In order to form the above roughened surface, in the roughening plating process, the current density multiplied by the processing time value must be set at 20 (A/dm ² ) ‧ seconds or more and 250 (A/dm ² ) ‧ seconds or less. When the value is less than 20 (A/dm ² ) ‧ seconds, after the silane coupling agent treatment, the height of the roughened particles on the roughened surface is difficult to form at least 0.05 μm, so it is not easy to ensure There is full adhesion. In addition, if it exceeds 250 (A/dm ² ) ‧ seconds, after the silane coupling agent treatment, the height of the roughened particles on the roughened surface is difficult to be less than 0.5 μm, so the transmission loss is likely to deteriorate. The above-mentioned current density multiplied by the processing time value is preferably 20 (A/dm ² ) seconds or more and less than 160 (A/dm ² ) seconds.

In order to form the above roughened surface, in the roughening plating process, the current density must be multiplied by the treatment time value, and the value divided by the molybdenum concentration is set at 0.2{(A/dm ² )‧sec}/( mg/L) or more. When the value is less than 0.2{(A/dm ² )‧sec}/(mg/L), although other characteristics can be satisfied, it is difficult to increase the BET surface area ratio of the surface treated by the silane coupling agent to 1.2 or more . In addition, even if the value exceeds 3.0{(A/dm ² )‧sec}/(mg/L), although the above roughened surface may be formed, it is difficult to reduce the roughened surface while satisfying other characteristics Cms tends to be less than 2.0. The current density is multiplied by the processing time value and divided by the Mo concentration value, preferably 0.2{(A/dm ² )‧sec}/(mg/L) or more, 3.0{(A/dm ² )‧sec} /(mg/L) or less, more preferably 0.2{(A/dm ² )‧ seconds}/(mg/L) or more and less than 1.0{(A/dm ² )‧ seconds}/(mg/L).

In order to form the above roughened surface, preferred roughening plating treatment conditions are disclosed below.

-Roughening plating treatment conditions-

Cu: 10~30g/L

H ₂ SO ₄ : 100~200g/L

Bath temperature: 20~30℃

Molybdenum concentration: 50~600mg/L

Velocity between electrode gaps: 0.15~0.4m/sec

Current density: 15~70A/dm ²

Current density × processing time: 0.1 to 10 seconds

Current density × processing time: 20 ~ 250 (A/dm ² ) ‧ seconds

Current density × treatment time ÷ molybdenum concentration: 0.2~3.0{(A/dm ² )‧sec}/(mg/L)

In addition, the addition of molybdenum to the plating solution refers to a form in which molybdenum is dissolved as ions, as long as it does not contain the metal impurities that change the pH of the copper sulfate plating solution and are incorporated into the copper plating film, there is no particular limit. For example, an aqueous solution of molybdate (for example, sodium molybdate or potassium molybdate) may be added to the copper sulfate plating solution.

<metal treatment layer>

When the surface-treated copper foil of the present invention has a metal-treated layer, the method of forming the metal-treated layer is not particularly limited, and can be formed by a general method. For example, taking the case of forming a metal treatment layer having nickel, zinc, and chromium as an example, the metal treatment layer can be formed in the following conditions, for example, in the order of nickel plating, zinc plating, and chromium plating.

(Nickel plated)

Ni: 10~100g/L

H ₃ BO ₃ : 1~50g/L

PO ₂ : 0~10g/L

Bath temperature: 10~70℃

Current density: 1~50A/dm ²

Processing time: 1 second to 2 minutes

pH: 2.0~4.0

〔Galvanized〕

Zn: 1~30g/L

NaOH: 10~300g/L

Bath temperature: 5~60℃

Current density: 0.1~10A/dm ²

Processing time: 1 second to 2 minutes

〔chrome〕

Cr: 0.5~40g/L

Bath temperature: 20~70℃

Current density: 0.1~10A/dm ²

Processing time: 1 second to 2 minutes

pH: below 3.0

In the surface-treated copper foil of the present invention, the amount of silicon elements present on the roughened surface (that is, the amount of silicon elements contained in the silane coupling agent layer) is preferably 0.5 μg/dm ² or more and less than 15 μg /dm ² . By setting the amount of the silicon element to 0.5 μg/dm ² or more and less than 15 μg/dm ² , while suppressing the amount of silane coupling agent used, it can effectively improve the adhesion with the resin. The amount of silicon element contained in the silane coupling agent layer is more preferably 2 μg/dm ² or more and less than 8 μg/dm ² .

The silane coupling agent is appropriately selected according to the molecular structure (type of functional group, etc.) of the resin constituting the resin layer laminated with the surface-treated copper foil of the present invention. Among them, the silane coupling agent is preferably an epoxy group, an amine group, a vinyl group, a (meth)acryloyl group, The styrene group, urea group, isocyanurate group, mercapto group, sulfide group, and isocyanate group select at least one functional group. "(Meth)acryloyl" means "acryloyl and/or methacryloyl".

By the treatment of the silane coupling agent on the surface of the copper foil on which roughened particles have been formed, it can be treated in a general manner. For example, a solution (coating liquid) of a silane coupling agent is prepared, and the coating liquid is applied to the surface of the copper foil on which roughened particles have been formed and dried, thereby allowing the silane coupling agent to adsorb or even bind to the On the surface of the copper foil on which roughened particles are formed. As the above coating liquid, for example, the solution used may be a silane coupling agent containing pure water at a concentration of 0.05 wt% to 1 wt%.

The coating method of the above coating liquid is not particularly limited. For example, in a state where the copper foil is inclined, the coating liquid can be evenly flowed on the surface on which roughened particles have been formed, and after removing excess liquid using a roller Heat and dry, spray the coating liquid on the copper foil between the rollers with the surface where the roughened particles have been formed facing down, and then remove the excess liquid with the rollers, perform heating and drying, etc. cover. The coating temperature is not particularly limited, and it is usually carried out at 10 to 40°C.

[Copper-clad laminates for printed wiring boards]

The copper-clad laminate for printed wiring boards of the present invention (hereinafter, abbreviated as "copper-clad laminate of the present invention") has a layered resin layer (resin on the roughened surface of the surface-treated copper foil of the present invention) Substrate). The resin layer is not particularly limited, and the resin layer used may be a resin layer generally used in copper-clad laminates used for producing printed wiring boards. For example, a glass epoxy-based halogen-free low-dielectric resin substrate used in rigid boards (hard printed wiring boards) may be used, or flexible Polyimide-based low-dielectric resin substrates often used in substrates.

The method of laminating the surface-treated copper foil and the resin substrate is not particularly limited. For example, the copper foil and the resin substrate are bonded by a hot press forming method using a hot press machine. The pressing temperature in the above hot press forming method is preferably set to about 150 to 400°C. In addition, the pressure surface pressure is preferably set to about 1 to 50 MPa.

The thickness of the copper-clad laminate is preferably 10 to 1000 μm.

〔Printed wiring board〕

The printed wiring board of the present invention is produced using the copper-clad laminate of the present invention. That is, the copper clad laminate of the present invention is subjected to etching and other treatments to form a conductor circuit pattern, which can be formed by a general method or mounted with other members as required.

Examples

Hereinafter, the present invention will be described in more detail based on examples. In addition, the following is an example of the present invention. In the practice of the present invention, various forms can be adopted as long as they do not deviate from the gist of the present invention.

〔Copper foil manufacturing〕

As the copper foil used as the base material for roughening treatment, electrolytic copper foil or rolled copper foil is used.

In Examples 2 to 4, 6 to 16, Comparative Examples 1 to 4, 6, 7 and Reference Example 1, an electrolytic copper foil with a thickness of 12 μm manufactured under the following conditions was used.

<Manufacturing conditions of electrolytic copper foil>

CuSO ₄ : 280g/L

H ₂ SO ₄ : 70g/L

Chlorine concentration: 25mg/L

Bath temperature: 55℃

Current density: 45A/dm ²

additive

‧Sodium 3-mercapto 1-propane sulfonate: 2mg/L

‧Hydroxyethyl cellulose: 10mg/L

‧Low molecular weight glue (MW 3000): 50mg/L

In Examples 1, 5 and Comparative Example 5, commercially available 12-μm refined copper rolled foil (manufactured by UACJ Co., Ltd.) was used to perform degreasing treatment under the following conditions.

<Degreasing treatment conditions>

Degreasing solution: aqueous solution of cleaning agent 160S (made by Meltec Corporation)

Degreasing solution concentration: 60g/L aqueous solution

Bath temperature: 60℃

Current density: 3A/dm ²

Power-on time: 10 seconds

[Form roughening surface]

A rough plating process is performed on one side of the copper foil by electroplating. The roughening plating treatment surface is composed of the following roughening plating solution basic bath composition, the molybdenum concentration is set as described in Table 1 below, and the flow velocity, current density, and processing time between the electrode gaps are set to As described in Table 1 below, the roughened plated surface was formed. The molybdenum concentration is adjusted by adding an aqueous solution in which sodium molybdate has been dissolved in pure water to the basic bath.

<Basic bath composition of roughening plating solution>

Cu: 25g/L

H ₂ SO ₄ : 180g/L

Bath temperature: 25℃

<gold-forming metal processing layer>

Next, for Examples 1 to 6, 8 to 16 and Comparative Examples 1 to 3, 5 to 7, as described above On the roughened plating treatment surface formed as described above, metal plating was performed in the order of Ni, Zn, and Cr under the plating conditions described in Table 2 to form a metal treatment layer.

<nickel plating>

Ni: 40g/L

H ₃ BO ₃ : 5g/L

Bath temperature: 20℃

pH: 3.6

<galvanized>

Zn: 2.5g/L

NaOH: 40g/L

Bath temperature: 20℃

〔chrome〕

Cr: 5g/L

Bath temperature: 30℃

pH: 2.2

<Coating with silane coupling agent (forming roughened surface)>

For Examples 1 to 16 and Comparative Examples 1 to 7, the entire surface of the plating treatment surface (the surface of the metal treatment layer if a metal treatment layer has been formed) was applied to the cities listed in Table 2 After the solution (30°C) of the silane coupling agent was sold, the excess solution was removed with a squeegee, and it was dried in the atmosphere at 120°C for 30 seconds to form a roughened surface. The preparation method of each silane coupling agent solution is as follows.

3-Glycidoxypropylmethyldimethoxysilane (KBM-402 manufactured by Shin-Etsu Chemical Co., Ltd.): Prepare a 0.3 wt% solution with pure water.

3-Aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.): Prepare a 0.25 wt% solution with pure water.

Vinyltrimethoxysilane (KBM-1003 manufactured by Shin-Etsu Chemical Co., Ltd.): Add sulfuric acid to pure water to prepare a 0.2wt% solution by adjusting the solution to pH3.

3-Methacryloxypropylmethyldimethoxysilane (KBM-502 manufactured by Shin-Etsu Chemical Co., Ltd.): Add sulfuric acid to pure water to adjust the solution to pH 3 to prepare a 0.25wt% solution .

3-Isocyanatopropyl triethoxysilane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd.): Add sulfuric acid to pure water to prepare a 0.2 wt% solution by adjusting the solution to pH3.

3-Ureidopropyltriethoxysilane (KBE-585 manufactured by Shin-Etsu Chemical Co., Ltd.): 1:1 ethanol and pure water are mixed, and a 0.3 wt% solution is prepared from the mixed solution.

[Measure the average height of coarse particles]

The cross-section parallel to the thickness direction of the copper foil obtained by ion milling was observed by SEM image, and the average height of the roughened particles on the roughened surface was obtained. The details are as follows.

The SEM image shown in FIG. 1 is a cross section parallel to the thickness direction of the roughened surface (surface after the silane coupling agent treatment) of the surface-treated copper foil manufactured in Example 5. In the same section, the top and bottom of the head of the roughened particles can be confirmed in the cross-section of each surface-treated copper foil, and the magnification is adjusted so that about ten roughened particles can be observed. SEM images were observed for five different fields of view under restrictions. Measure the height of the roughened particles with the highest height in the five fields of view of a surface-treated copper foil, and set the average of the five measured values (maximum value) as the roughening of the surface-treated copper foil The average height of the roughened particles in the treatment surface.

The method of measuring the height of the coarsened particles will be described in detail using the drawings. As shown in FIG. 1, for the roughened particles to be measured, the shortest distance of the straight line connecting the left and right bottoms (the straight line connecting points a and b) is the longest, and the top of the head of the roughened particles (point c) is The shortest distance between the straight lines connecting point a and point b is set as the height H of the coarsened particles.

The SEM image shown in FIG. 2 is a cross section parallel to the thickness direction of the roughened surface (surface after the silane coupling agent treatment) of the surface-treated copper foil produced in Example 6. When the coarsened particles form a branched state as shown, the whole including the branched structure is regarded as one coarsened particle. That is, the shortest distance between the bottom line of the left and right bottoms (the line connecting point d and point e) formed into dendritic roughened particles is the longest, and the top of the head (point f) of the roughened particles is connected to point d The shortest distance between the straight line at point e is set as the height H of the coarsened particles.

The results are shown in Table 3 below.

[Determination of BET surface area ratio A]

The calculation of the BET surface area ratio A is obtained by dividing the surface area of the roughened surface measured by the BET method (BET measurement surface area) by the sample cutout area forming the plan view area.

The BET measurement surface area was measured using a gas adsorption pore distribution measurement device ASAP2020 model manufactured by Micromeritics Co., Ltd. using the krypton gas adsorption BET multipoint method. Before the measurement, the pretreatment system was dried under reduced pressure at a temperature of 150°C for 6 hours.

The sample (copper foil) used for the measurement was cut out to form about 3 g of 3 dm ² and then cut into a 5 mm square, and then introduced into the measurement device.

In the surface area measurement by the BET method, since the entire surface area of the sample introduced into the device is measured, it is impossible to measure only the roughened surface of the above-mentioned surface-treated copper foil that has been roughened on one side. Surface area. Here, the BET surface area ratio A is actually It is calculated as follows.

<Calculate BET surface area ratio A>

The surface area ratio of the surface not subjected to the roughening treatment (the surface on the opposite side to the roughening treatment surface) is 1, that is, the same as the sample cut-out area, and the BET surface area ratio A is calculated by the following formula.

(BET surface area ratio A) = [(BET measured surface area)-(sample cut-out area)]/(sample cut-out area)

In addition, in the surface area measurement of the BET method, the surface area of the surface (side surface) other than the roughened surface and the surface not roughened is also measured. However, the thickness of the foil estimated by the present invention (for example, even the maximum In the area of about 120 μm), the side surface occupies a very small proportion in the total top view area, which can actually be ignored.

As shown in Reference Example 1, in the object that has not been roughened on the surface, due to the measurement principle of the BET method, the BET measurement surface area may be smaller than the cut-out area (that is, the BET surface area is less than 1 Case). On the other hand, when the surface is formed with fine irregularities due to the roughening treatment, the BET method is applied, so that fine irregularities and the like can be detected with high sensitivity, and as a result, the BET surface area ratio A exceeds 1.

[Determination of laser surface area ratio B]

The laser surface area ratio B is calculated based on the measured surface area using a laser microscope VK8500 (manufactured by Keyence Corporation). In more detail, the roughened surface of the sample (copper foil) was observed at a magnification of 1000 times, and the three-dimensional surface area of the portion with a plan view area of 6550 μm ^{2 was} measured, and the laser surface area ratio B was obtained by dividing the three-dimensional surface area by 6550 μm ² . The measurement pitch was set to 0.01 μm. The results are shown in Table 3.

〔Calculate fine surface coefficient Cms〕

The fine surface coefficient Cms is calculated using the above-mentioned BET surface area ratio A and the above-mentioned laser surface area ratio B according to the following formula. The results are shown in Table 3 below.

Fine surface coefficient Cms=BET surface area ratio A/laser surface area ratio B

[Determination of Nickel]

The amount of nickel element (mg/dm ² ) was measured by marking the surface of the sample with the coating without roughening plating, and cutting out a 10 cm square to heat the mixed acid (nitric acid 2: hydrochloric acid 1: Pure water 5 (volume ratio)) After dissolving only the surface part, the mass of nickel in the obtained solution was analyzed by atomic absorption spectrometry (model: Z-2300) manufactured by Hitachi High-Tech Science Co., Ltd. Method for quantitative analysis. The results are shown in Table 3 below as the amount of nickel element. In addition, the amount of nickel element measured in the above manner, that is, the amount of nickel element contained in the metal treatment layer.

[Measurement of Silicon]

The amount of silicon element (μg/dm ² ) in the roughened surface (that is, the amount of silicon element contained in the silane coupling agent layer) is set to be the same as the amount of nickel element, and quantitative analysis is performed by atomic absorption analysis And get the amount of silicon. The results are shown in Table 3 below as the amount of silicon element.

[Evaluation of high frequency characteristics]

The transmission loss in the high-frequency band is measured as an evaluation of high-frequency characteristics. The roughened surface (surface treated with a silane coupling agent) of the surface-treated copper foil having a roughened surface manufactured in the above examples and comparative examples was posted to a bonding polyimide manufactured by KANEKA Corporation PIXEO of imine (FRS-522 thickness 12.5 μm), pressurized at a temperature of 350° C. and a surface pressure of 5 MPa for 20 minutes, used as a copper-clad laminate, and then formed a microstrip line with a width of 100 μm and a length of 40 mm (microstripline) ) Transmission path. In this transmission path, a network analyzer is used to transmit high-frequency signals up to 100 GHz, and the transmission loss is measured. The characteristic impedance is 50Ω.

The measured value of the transmission loss is that the smaller the absolute value, the smaller the transmission loss, which means that it has good high-frequency characteristics. Table 4 shows the evaluation results of the transmission loss in 20 GHz and 70 GHz. The evaluation criteria are as follows.

<20GHz transmission loss evaluation criteria>

◎: Transmission loss is above -6.2dB

○: Transmission loss is less than -6.2dB to -6.5dB

×: Transmission loss is less than -6.5dB

<70GHz transmission loss evaluation criteria>

◎: Transmission loss is above -20.6dB

○: Transmission loss is less than -20.6dB to -24.0dB

×: Less than -24.0dB

Furthermore, based on the above-mentioned evaluation results of the transmission loss, the comprehensive evaluation is based on the high-frequency characteristics of the following evaluation criteria. The results are shown in Table 4 below.

<Comprehensive Evaluation Criteria for High Frequency Characteristics>

◎ (Excellent): The evaluation results of the transmission loss of 20 GHz and the transmission loss of 70 GHz are both ◎.

○ (Good): The evaluation result of the transmission loss of 20 GHz is ◎, and the evaluation result of the transmission loss of 70 GHz is ○.

△ (Pass): Although the evaluation result of the transmission loss at 70 GHz is ×, the transmission loss at 20 GHz is ◎ or ○.

× (Fail): The evaluation results of the transmission loss of 20 GHz and the transmission loss of 70 GHz are both ×.

[Evaluation of heat-resistant adhesion]

A copper-clad laminate was produced in the same manner as the copper-clad laminate produced in the above [Evaluation of High Frequency Characteristics], and the copper foil portion of the obtained copper-clad laminate was marked with an adhesive tape having a width of 10 mm. After the copper-clad laminate was etched with copper chloride, the tape was removed, and a 10 mm-wide circuit wiring board was produced. After heating the circuit wiring board in a heating furnace at 150°C for 1000 hours, using a Tensilon (tensile/compression) tester manufactured by Toyo Seiki Co., Ltd. at room temperature, the circuit wiring part (copper) with a width of 10 mm Foil part), the peeling strength when peeling from the polyimide resin base material was measured at a speed of 50 mm/min in a 90-degree direction. The resulting measurement The value is used as an index to evaluate the heat-resistant adhesion according to the following evaluation criteria. The results are shown in Table 4 below.

<Evaluation criteria for heat-resistant adhesion>

◎: Peel strength is 0.7kN/m or more

○: Peel strength is 0.6kN/m or more and less than 0.7kN/m

△: Peel strength is 0.5kN/m or more and less than 0.6kN/m

×: Peel strength is less than 0.5kN/m

[Evaluation of Etching]

If the amount of metal attached to the surface of the copper foil is too large, when etching is performed to form a circuit, metal residues are likely to remain on the surface of the resin substrate. When the metal residues remain on the surface of the resin substrate, it will cause the bad situation that the insulation resistance decreases. Especially because the etching rate of nickel is lower than that of copper, when the amount of adhesion is too large, the insulation will be reduced, and short circuits are likely to be caused.

Here, using the copper-clad laminate manufactured in the same manner as the copper-clad laminate produced in the above [Evaluation of High Frequency Characteristics], the insulation resistance value was measured in accordance with 2.5.17 of IPC Test Specification TM-650. In more detail, in order to cut out the copper-clad laminate to a size of 10 cm×10 cm, a copper foil pattern was formed by etching. The surface impedance was measured three times in accordance with experimental specifications, and the average of the three measured values was obtained. Using the average value of the obtained surface impedance values as an index, the evaluation of the etchability was performed according to the following evaluation criteria. The results are shown in Table 3 below.

<Evaluation criteria for etching properties>

◎: The average value of the surface impedance value is 1014Ω or more.

○: The average value of the surface impedance value is 1013 Ω or more and less than 1014 Ω.

×: The average value of the surface impedance value is less than 1013Ω.

〔Comprehensive Evaluation〕

Based on the above-mentioned high-frequency characteristics, heat-resistant adhesiveness and etching properties, comprehensive evaluation is carried out based on the following evaluation criteria.

<Evaluation criteria for comprehensive evaluation>

AA (Excellent): The comprehensive evaluation of the high-frequency characteristics, the evaluation results of the heat-resistant adhesiveness and the etchability are all ◎.

A (good): There is one of the ○ evaluations in the comprehensive evaluation of high-frequency characteristics, heat-resistant adhesiveness, and etching properties, and the remaining two evaluations are ◎.

B (pass): does not belong to any of the above AA and A status, but there is no status evaluated as ×.

C (Fail): At least one of the comprehensive evaluation of high-frequency characteristics, heat-resistant adhesiveness, and etching property is ×.

Here, the results shown in the above tables are discussed.

Comparative Example 1 is an example in which the average height of the roughened particles present on the roughened surface of the surface-treated copper foil is smaller than that specified by the present invention. When the surface-treated copper foil of Comparative Example 1 is used to produce a copper-clad laminate, a result of deterioration of the heat-resistant adhesiveness between the copper foil and the resin substrate.

Comparative examples 2, 3, 6 and 7 are respectively the roughened surface of the surface-treated copper foil The BET surface area ratio is smaller than the example specified in the present invention. When the surface-treated copper foils of Comparative Examples 2, 3, 6 and 7 were used to produce a copper-clad laminate, the result of deterioration of the heat-resistant adhesiveness between the copper foil and the resin substrate.

Comparative Examples 4 and 5 are examples in which the average height of the roughened particles present on the roughened surface of the surface-treated copper foil is greater than that specified by the present invention. When the surface-treated copper foils of Comparative Examples 4 and 5 were used to fabricate a copper-clad laminate and a conductor circuit was formed, the result of a significant deterioration in high-frequency characteristics occurred.

In addition, Reference Example 1 is an example in which roughening treatment was not performed on the copper foil. In the case of using the copper foil of Reference Example 1 to produce a copper-clad laminate, the result is that the heat-resistant adhesiveness between the copper foil and the resin substrate greatly deteriorates.

In contrast, the average height of the roughened particles formed on the roughened surface of the surface-treated copper foil is within the range specified by the present invention, and the BET surface area ratio of the roughened surface also meets the requirements of the present invention The surface-treated copper foils of Examples 1 to 16 are used to produce copper-clad laminates, and the copper foil and the resin substrate exhibit excellent heat-resistant adhesion. In addition, the conductor circuit formed by the copper-clad laminate using the surface-treated copper foil of Examples 1 to 16 can effectively suppress transmission loss even when transmitting high-frequency signals, and has excellent insulation reliability.

This application is for claiming the priority of Japanese Patent Application No. Japanese Patent Application No. 2015-240006 filed in Japan on December 9, 2015. The priority here is to refer to the priority, and its contents are included as part of the contents of this specification.

Claims (8)

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on the surface on which roughened particles are formed, characterized in that, on the surface of the silane coupling agent layer, the average height of the roughened particles is 0.05 μm or more and is not Up to 0.5 μm, the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more. The surface-treated copper foil for printed wiring boards as claimed in item 1 of the patent scope, wherein the average height of the roughened particles on the surface of the silane coupling agent layer is 0.05 μm or more and less than 0.3 μm. For example, the surface-treated copper foil for a printed wiring board according to item 1 or 2 of the patent application scope, wherein, on the surface of the silane coupling agent layer, the fine surface coefficient Cms is 0.6 or more and less than 2.0. The surface-treated copper foil for printed wiring boards as claimed in item 1 or 2 of the patent scope, wherein the surface on which the roughened particles are formed has a metal treatment layer containing nickel, and the amount of nickel element contained in the metal treatment layer is 0.1mg/dm ² or more and less than 0.3mg/dm ² . The surface-treated copper foil for printed wiring boards as claimed in item 1 or 2 of the patent application, wherein the amount of silicon element contained in the silane coupling agent layer is 0.5 μg/dm ² or more and less than 15 μg/dm ² . The surface-treated copper foil for printed wiring boards as claimed in item 1 or 2 of the patent application, wherein the silane coupling agent has a group selected from epoxy, amine, vinyl, (meth)acryl, styryl, At least one functional group among urea group, isocyanurate group, mercapto group, sulfide group, and isocyanate group. A copper-clad laminate for a printed wiring board, characterized in that a resin layer is laminated on the surface of the silane coupling agent layer of the surface-treated copper foil for a printed wiring board according to any one of claims 1 to 6. A printed wiring board that uses the copper-clad laminate for printed wiring boards as claimed in item 7 of the patent scope.